Confronting one of psychiatry's most wrenching problems, Maryland's medical disciplinary board has suspended the license of an esteemed psychiatrist who admitted to having a sexual affair with a patient suffering from depression and multiple personality disorder.

Dr. John Hamilton, now forbidden to treat patients for at least a year, is the deputy medical director for the American Psychiatric Association who is credited with co-authoring an APA manual that set national standards for patient care. He also served stints as superintendent of two state psychiatric hospitals.

The patient, a 40-year-old woman from Howard County, had an (( extensive history of emotional problems when she came under his care in March 1988 as a severely shaken and suicidal inpatient at Howard County Hospital. She said her problems stemmed partly from two past sexual assaults, one of them while she was a patient in a psychiatric unit at the Johns Hopkins Hospital.

"This is a very serious issue," John Blamphin, a spokesman for the American Psychiatric Association, said yesterday. He said the organization, based in Washington, had just learned of the ruling, and he was not sure if Dr. Hamilton would be allowed to remain in his post.

Some studies have suggested that 10 percent of all therapists have allowed warm feelings toward clients to progress from fantasy to verbal suggestions and -- ultimately -- sexual contact. Mr. Blamphin acknowledged that the problem has caused the profession much self-examination. In its code of ethics, the national psychiatric group clearly condemns any sexual contact

between doctor and patient: "Sexual activity with a patient is unethical," it says. "Sexual involvement with one's former patients generally exploits emotions deriving from treatment and therefore is almost always unethical."

The State Board of Quality Assurance, which made its ruling public yesterday, called Dr. Hamilton's conduct "unethical" and a violation of state law.

Dr. Hamilton referred all questions to his lawyer, George L. Russell Jr. "He's going to obey the order," Mr. Russell said. "But I won't comment any further than that."

In an interview yesterday, the woman said Dr. Hamilton initiated the affair in August 1988 during an office visit. She said she was drawn into the relationship because she gave him "god" status ** and believed he really loved her, but was deeply worried because it seemed inappropriate conduct for a doctor and patient.

She said she finally broke off the relationship in May of 1990 -- disgusted when she found a stash of pornographic magazines in his suitcase while the two were spending several days in New York. He was there attending the national convention of the American Psychiatric Association, and had invited her along.

"I felt reduced to a subhuman being," said the woman, whose name has been kept confidential. Now, "I have no belief or trust in myself. I still have nightmares. I hear his voice. I've stayed virtually inside my house in months except to get groceries. I haven't worn a dress since October."

The woman, a former flight attendant and secretary, said she was glad the board ordered him to stay away from patients for at least a year but wished the sanctions had been harsher. She said the two-year affair had left her feeling manipulated, betrayed and incapable of trusting herself or anyone else.

"This could happen to any woman. It doesn't matter if the woman has 30 degrees. All it takes is her low self-esteem. All he has to do is to intermittently keep her off balance to fill his own needs, to have her doubt her own perceptions."

In a 15-page document that was made public yesterday, the state Board of Physician Quality Assurance forbade Dr. Hamilton to handle anything other than "administrative duties" in the practice of psychiatry for at least a year. The board did not define what those duties might be.

The board also ordered him to see a psychiatrist during a five-year probation. One year into his probation, he can ask permission to treat patients. Even if the board agrees, he would be allowed to treat male patients only until March 1995 at the earliest. A year later, the board could remove all restrictions on his practice but could impose harsher penalties should it see fit.

Dr. Hamilton waived his right to a hearing where he would have had the right to contest the allegations. Instead, he agreed to the penalties and admitted to a narrative of his affair. This included statements that he visited the woman at her home and she accompanied him to "social events in public."

He also admitted that he had confessed to a minister that he "had crossed some lines" and "engaged in inappropriate contact with a patient of a physical/sexual nature," according to the consent decree.

Despite the affair, Dr. Hamilton continued to provide outpatient therapy to the woman until June 1989. The romantic relationship continued for almost a year more, however.

With anger in her voice, the woman said she had trouble finding another therapist to treat her. Several refused to have anything to do with her when she described her affair with Dr. Hamilton, she said, although she eventually entered into therapy with a psychologist.

Sexual contact with a patient is unethical "because it violates psychiatrist-patient boundaries that are necessary for an effective therapeutic relationship" and "confuses the patient as to the nature and extent of those boundaries," the board said. Such activity also diminishes the patient's trust in therapists and "provides gratification to the psychiatrist at the patient's expense."

Dr. Hamilton served as superintendent of the Spring Grove Hospital Center during a 12-year stint that ended in 1985. Earlier, he headed the Clifton T. Perkins Hospital Center for the criminally insane.

Still pending is a civil suit, in which the woman is seeking monetary damages against Dr. Hamilton. Joann Suder, her lawyer, said the case claims sexual misconduct and professional abandonment of his patient.

Dr. Bruce Hershfield, president of the Maryland Psychiatric Society, greeted news of the sanctions with sadness.

"John Hamilton is a very well-known psychiatric figure," he said. "He's done a lot of good for people in this area."

But he said: "We have no tolerance at all for this. Psychiatrists are clearly instructed to maintain boundaries in their interactions with patients."